The invention relates to a lightweight frame for supporting a facing material in a prefabricated panel. Particularly, the invention relates to a prefabricated panel useful for building walls. Most particularly, the invention relates to prefabricated panels having stone facing.
Due to its physical and esthetic qualities, stone has long been one of the most preferred materials for the exterior facing of buildings.
Traditional techniques for utilizing stone as an exterior facing required walls of stone which would be self supporting vertically as well as stable horizontally over the height of the structure.
Modern construction techniques have been directed to reducing the amount and cost of the stone required to erect a structure and to reduce the weight of the structure so that smaller foundations are required.
One solution to reduce the amount of stone requird to erect a structure involves building a backup wall of cinder blocks or reinforced concrete to which a relatively thin facing of the more expensive natural stone is attached. The double wall construction remains relatively heavy however and requires a double operation since the backup wall has to be built before the stone facing can be applied. The double wall system has proven to be both time consuming and expensive, particularly in multi-store structures which require elaborate scaffolding for the full height of the structure.
With the advent of mechanized apparatus such as cranes and motorized lifting apparatus, it became advantageous to "prefabricate" large sections of the exterior wall under controlled conditions in a factory, transport the sections to the building site and fasten them to the building framework. The prefabricated sections were normally reinforced concrete to which the stone facing was laminated during the casting operation. The prefabricated sections were excessively heavy, required large foundations and presented formidable engineering problems in attaching them to the building structure.
In view of the disadvantages of prefabricated sections in which a stone facing is laminated to a reinforced concrete panel, attempts have been made to develop a prefabricated exterior wall panel system in which stone facing is supported on a metal framework. The attempts have not been commercially successful due to complex fabrication techniques and the use of mechanical connectors at the edges of the stone facing.
The steel framework utilized in the prefabricated panels was usually fabricated of metal "channel studs" similar to those used to replace wooden studs in erecting interior partitions. Channel studs do not readily adapt themselves to easy cutting and fitting nor do they facilitate connection between the frame and the stone. In addition, the edge connectors utilized to join the stone to the frame caused considerable breakage during movement of the prefabricated panels.
It is an object of the present invention to provide a lightweight rigid metal frame to support stone facing in a prefabricated panel. It is another object of the invention to provide a metal frame which lends itself to easy attaching of the stone to the frame. It is a further object of the invention to provide a means of fastening the stone firmly to the frame without imposing excessive local stresses. It is another object of the invention to provide a system which can accomodate stones of a relatively large surface area while maintaining their surfaces substantially in a single plane.
Another object of the invention is to provide a frame which can be readily manufactured in a variety of lengths and widths. A further object of the invention is to provide a frame which can be manufactured in a variety of lengths and widths, with a minimum of custom cutting, fitting and fastening, using assembly line techniques.
In addition, it is an object of the invention to provide a prefabricated panel which is easy to lift, handle and transport. A further object of the invention is to provide a prefabricated panel which can be simply and dependably fastened to the building structure.